The nation’s third largest health insurance company is the latest to leave the individual policy market in Indiana in another sign of diminishing competition to benefit consumers who purchase policies through a state insurance exchange under the federal health care overhaul.

Aetna has informed the Indiana Insurance Department of Insurance that it intends to cancel all individual policies December 1st. Aetna’s notice was included in a letter last week from Deputy Insurance Commissioner Robyn Crosson to federal officials.

Crosson says Aetna’s leaving the individual market over a health care overhaul rule that essentially requires insurers to dedicate 80 percent of the premiums they collect to medical care. If less than that, they must pay rebates to policyholders. Indiana wants to phase in the rule over several years.